Oh please, for all intents and purposes, the gist of the GP is 'oh it's the Economist, they're a bunch of shills, so they're wrong'. I'm not going to argue nonsensical things like what exactly is an ad hominem, it's crystal clear that the GP intended to dismiss the message of the article by saying that because it's from the Economist, it's automatically wrong; i.e., that it's wrong because of who said it and their ideological background, rather than the substance of what was said. If that's not an ad hominem, I don't know what is.